(a) Field of the Invention
The present invention relates to an interference recognition-based device-to-device (D2D) resource allocation method and an apparatus therefor. More particularly, the present invention relates to an interference recognition-based D2D resource allocation method and an apparatus therefor that use cooperation between a base station and a D2D.
(b) Description of the Related Art
Recently, a device-to-device (D2D) communication in a cellular system is under research and development (R&D) and standardization. The D2D communication allows positionally-adjacent terminals to directly communicate each other without using an existing infrastructure such as a base station or an access point (AP).
FIG. 1 illustrates a schematic diagram of a D2D communication. The existing infrastructure-based communication is a method that terminals communicate each other through a base station, and the D2D communication performs direct communication between terminals without going through a base station.
In the cellular system, when the D2D communication is performed between the positionally adjacent terminals, since a load of the base station may be distributed and a relatively short-range communication may be performed, consumption power of the terminal may be reduced and a latency may also be reduced. In view of an overall system, the D2D terminal shares the same frequency with the existing cellular terminal to spatially reuse the frequency, thereby improving use efficiency.
The D2D communication enables a new service based on proximity and improves frequency efficiency of the cellular system at the same time. Generally, the D2D terminal shares an existing cellular frequency resource of the cellular terminal so as to improve frequency efficiency. However, in the process of sharing the frequency resource, since interference between the D2D terminal and the cellular terminal may occur, a resource allocation technology that can properly control the interference is required.
Since a D2D link shares a frequency resource with a cellular link, interference between the D2D link and the cellular link necessarily occur. When the interference is not properly controlled, the D2D communication is difficult and even performance for a cellular user may deteriorate.
In a single cell environment, when the D2D link shares a cellular uplink resource, there may be three generable kinds of interference. That is, there are the interference that the cellular terminal gives to D2D terminal, the interference that the D2D terminal gives to the base station, and the interference between the D2D links. An effective interference control is significantly important for a cellular-based D2D communication. Here, the interference control may be implemented through a resource allocation.
A difference between the cellular-based D2D communication and the D2D communication in a non-licensed frequency bandwidth is that a base station for the cellular-based D2D communication may be involved in D2D communication control processes including a resource allocation process.
FIG. 2 is a drawing illustrating cellular-based D2D communications classified into three types depending on a degree in which a base station is involved. In the case of a distributed-D2D, when the data signal and the control signal are transmitted between the terminals, the base station is not involved therein. In the case of a centralized-D2D, only the data signal is directly transmitted between the terminals, and the control signal is transmitted by the base station.
Further, although the centralized-D2D method in which the base station collects channel information or distance information of the links and allocates D2D resource based on the collected information has good performance, a load of a signal process therefor is heavy, and it may be difficult to apply the centralized-D2D method in a situation that the base station can normally not operate as in a disaster situation. Further, since the distributed-D2D is a method in which the D2D terminal recognizes peripheral interference and allocates resources by itself, although there is no load burdened on the base station, since the resource allocation for a cellular user is dynamically changed, which may not be easily controlled by the D2D terminal.
The background art of the present invention is disclosed in the Korean Patent Laid-Open Publication No. 2008-0028347 (laid-open on Mar. 31, 2008).
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.